<p>The <code>filter</code> attribute becomes a special attribute only in case it's defined as an object, instead of the usual SVG syntax (e.g. <code>"url(#myfilter)"</code>).
    If it's defined as an object, it must have the form defined by by the <a href="#dia.Paper.prototype.defineFilter">filterGradient()</a> paper method.</p>

<pre><code>element.attr('rect/filter', {
    name: 'dropShadow',
    args: {
        dx: 2,
        dy: 2,
        blur: 3
    }
});</code></pre>

